The typical computer system is susceptible to dust. For example, dust may travel into an area of the computer system containing computer hardware. Such dust may make contact with exposed conductive structures (e.g., dust may gather on adjacent surface traces of a circuit board, on neighboring circuit board pads or device contacts, etc.) and collect moisture causing lowered electrical resistance and perhaps even undesired electrical shorts between the conductive structures. These are known as hygroscopic dust failures. Such a situation may produce disadvantageous results such as corruption of electronic signals, a catastrophic fire, etc.
To prevent dust from entering the hardware areas of computer systems, some manufacturers equip their computer systems with air filters which remove dust from the air entering the systems, e.g., air flows generated by fan assemblies. Once the air filters have collected a certain amount of dust, the air filters no longer reliably allow sufficient air to pass into the computer systems for adequate hardware cooling. To prevent computer systems from overheating, users of the computer systems should change the air filters before the air filters become significantly clogged.
There are a variety of conventional approaches to determining when a user should change an air filter of a computer system. One conventional approach to determining when a user should change an air filter is to use a timer which measures hours of operation. In this approach (hereinafter referred to as the “conventional timer approach”), the user starts a timer (e.g., a background task running on the computer system). After a preset amount of time transpires (e.g., three months), the timer goes off and the computer system displays a notice to the user instructing the user to change the air filter.
In another conventional approach (hereinafter referred to as the “conventional temperature sensing approach”), the computer system includes a temperature sensing circuit which remains silent as long as the temperature within the computer system remains below a preset temperature threshold. When the temperature within the computer system rises above the preset temperature threshold due to clogging of the air filter (i.e., an abnormal temperature rise), the temperature sensing circuit signals the user to change the air filter.
In yet another approach (hereinafter referred to as the “conventional bleed hole approach”), the computer system includes a bleed hole and an anemometer circuit disposed within the bleed hole. When the air filter is clean, the air filter allows sufficient air to pass therethrough, and there is little or no air passing through the bleed hole. Accordingly, the anemometer circuit detects minimal air flow through the bleed hole and remains silent. However, following a period of operation, the capacity of the air filter decreases causing the amount of air passing through the bleed hole to increase. Eventually, the anemometer circuit determines that the air flow through the bleed hole exceeds a preset threshold and signals the user to change the air filter.